<button @click="up">从高到低</button>
  <button @click="down">从低到高</button>

export default {
  data() {
    return {
      itemList: [1, 2, 3, 4, 5, 6]
    };
  },
  methods: {
    // 从高到低
    up() {
    	this.itemList.sort((a, b) => {
            return a - b;
         });   
      //这个是另一种写法
      //function fn(a, b) {
      // return -(a - b);
      //}
      //this.a = this.a.sort(fn);
    },
    // 从低到高
    down(){
		this.itemList.sort((a, b) => {
            return b - a;
         }); 
	  //这个是另一种写法	
      //function fn(a, b) {
      //return (a - b);
      //}
      //this.a = this.a.sort(fn);
    }
  }
};
</script>